Electrical load management systems for allowing an electrical utility to control the load on the electrical system are known in the art. These systems operate to divert energy requirements to minimize electrical black-outs or "brown-outs". For example, U.S. Pat. No. 4,190,800 to Kelly, Jr. et at., entitled "Electrical Load Management System", assigned to the same assignee as the present invention, describes an electrical load management system wherein a utility command center monitors the use of electrical power and, when peak demand periods occur, transmits coded information by radio from the command center to remote receivers mounted proximate the electrical loads. In this patent, the transmitted signal includes address and command information that is decoded at the receivers. Receivers addressed by the command center pass command information over the distribution lines to the electrical loads, and thereby control the operation of the customers' power consuming devices.
Other load management systems utilize separate radio receivers at each customer's location, rather than providing a receiver at the distribution transformer as in the aforementioned patent. Examples of this type system include the types DCU-1120, -1170, -1180, -1190, and S2000A utility radio switches, otherwise described as digital control units or load control switches, manufactured by Scientific Atlanta, Inc., Atlanta, Ga., and the type REMS-100 radio switch manufactured by General Electric, King of Prussia, Pa. These utility radio switches incorporate an FM receiver that can receive a transmitted signal up to about 25 miles from a transmitter site located at a command center. The transmitter issues commands to temporarily remove power from a selected load. This self-contained receiver is typically mounted on or immediately adjacent to the electrical loads under control, and receives its power from the line that feeds the controlled loads. Switches, jumpers, or other means contained within the receiver configure the receiver to respond only to a particular address or set of addresses, so that different geographical areas, types of appliances, or numbers of consumers may be separately controlled.
A utility develops a wide range of electrical load management strategies for effectively utilizing the remotely controllable radio switches in response to various control scenarios. Typical load control scenarios depend upon a range of parameters, including temperature, humidity, utility customer's tolerance to temperature, and load management system technical performance. For example, a typical load management strategy is the maintenance of the operating duty cycle of selected electrical loads, such as air conditioning units, at a maximum rate of 50% for a control scenario involving a peak power consumption period during a summer afternoon with a 90 degrees average air temperature and a 50 percent humidity factor.
The most effective use of an electrical load management system is based upon applying the proper electrical load management strategy to an identified control scenario. However, the development of an effective electrical load management strategy during each likely control scenario requires the utility to monitor the operation of the electrical load management system during the control scenarios and thereby validate the effectiveness of the developed strategies.
A utility presently determines the effectiveness of an electrical load management system for a selected control scenario by collecting or monitoring energy consumption data for selected customers during predetermined data collection periods involving load management activities. Specifically, the utility compares the maximum energy consumed by the selected customers for each of these collection periods to the maximum energy that would be consumed by these customers in the absence of any load management activities by the electrical load management system.
The utility typically utilizes a load profile recorder located proximate to each customer's electrical load for recording power consumption by each utility customer during predetermined time intervals. The load profile recorder is connected to an electrical load via an energy consumption meter for recording energy consumption by an individual consumer during an extended period of time, typically at least a 30 day data collection period, thereby enabling the utility to determine energy usage patterns for the predetermined time intervals over the course of the collection period.
Upon the conclusion of the collection period, the recorded energy consumption data is forwarded from each load profile recorder to a central data processing site for data translation and evaluation. For certain types of load profile recorders, the utility sends personnel to each load profile recorder site to retrieve the recorded energy consumption data, which is typically recorded on magnetic tape or removable digital memory modules. Other load profile recorders include a telephone interface for sending the recorded energy consumption data via a telephone system to a data processing site either during a prescribed time or in response to an instruction transmitted by the data processing site. The utility then produces a report concerning the energy consumption data for the collection period and utilizes this report to evaluate the effectiveness and cost benefit of the electrical load management program.
Although utilizing a load profile recorder to store energy consumption data is useful for the evaluation of an electrical load management system, the utility necessarily assumes that each load control switch is properly operating in response to the utility's commands during the energy consumption data collection period because the load profile recorder only records energy consumption data and does not monitor or record the actual operation of the load control switch. Nevertheless, a random distribution of load control switches for any data collection period either will be inoperative or will not implement the utility's command for a load reduction because the load does not exceed the power consumption or duty cycle threshold set by the command to initiate the removal of the load. Furthermore, many types of load control switches utilize a load control delay function that prevents a group of these switches from instantaneously responding to a command to implement a load control operation. Instead, these load control switches remove an electrical load from the electrical distribution network only after a variable period of delay time lapses, thereby insuring that the energy supplied by the network is not instantaneously reduced in response to the command.
Consequently, a utility cannot accurately determine the effectiveness of an energy load management system utilizing load control switches merely by assuming that the power consumption data recorded by a load profile recorder during a collection period reflects the actual load reduction implemented by the utility's command for that particular time period. Therefore, a system is needed for monitoring and recording the control operations of individual load control switches, in combination with a monitoring system for recording the power consumption by the controlled load, to enable a utility to accurately determine the effectiveness of its electrical load management system. It would be highly advantageous to implement the system by combining the monitoring and recording functions with the known load control switching function to minimize manufacturing, installation, and maintenance costs.
Furthermore, utilities need a system for controlling a load and monitoring both control operations and power consumption, which further includes a two-way communications system for transmitting load control operation data and energy consumption data to a data processing center to insure a timely delivery of such data for rapid evaluation by the utility. In this manner, a utility may implement a selected control scenario for its electrical load management system during a first day, receive and begin evaluation of the collected data upon the conclusion of the first day, and revise the control scenario for implementation during the next day in response to the evaluation of the data collected during the first day. Consequently, this type of system insures that utility personnel can make timely decisions concerning the control of an electrical distribution network based upon more accurate electrical load management system performance information.